1. Field of the Invention
The present invention relates to a novel anthracene derivative and a radiation-sensitive resin composition. More particularly, the present invention relates to an anthracene derivative useful as an additive to a radiation-sensitive resin composition suitably used as a chemically-amplified resist for microfabrication utilizing various types of radiation such as deep ultraviolet rays such as a KrF excimer laser, ArF excimer laser, and F2 excimer laser, X-rays such as synchrotron radiation, and charged particle beams such as electron beams, and to a radiation-sensitive resin composition comprising the anthracene derivative.
2. Description of Background Art
In the field of microfabrication represented by the manufacture of integrated circuit devices, lithographic technology enabling microfabrication with a line width of 0.20 xcexcm or less has been demanded in order to increase the degree of integration.
A conventional lithographic process generally utilizes near ultraviolet rays such as i-line radiation. It is known in the art that microfabrication with a line width of a sub-quarter micron order or less using near ultraviolet rays is very difficult.
Therefore, use of radiation with a shorter wavelength has been studied for enabling microfabrication with a line width of 0.20 xcexcm or less. As radiation with a shorter wavelength, deep ultraviolet rays represented by a line spectrum of a mercury lamp and an excimer laser, X-rays, electron beams, and the like can be given. Of these, a KrF excimer laser (wavelength: 248 nm), an ArF excimer laser (wavelength: 193 nm), and an F2 excimer laser (wavelength: 157 nm) have attracted attention.
As a radiation-sensitive resin composition applicable to shorter wavelength radiation, a number of compositions utilizing a chemical amplification effect between a component having an acid-dissociable functional group and a photoacid generator which generates an acid upon irradiation (hereinafter called xe2x80x9cexposurexe2x80x9d) has been proposed. Such a composition is hereinafter called a xe2x80x9cchemically-amplified radiation-sensitive compositionxe2x80x9d.
As the chemically-amplified radiation-sensitive composition, Japanese Patent Publication No. H02-27660 discloses a composition comprising a polymer containing a t-butyl ester group of carboxylic acid or a t-butylcarbonate group of phenol and a photoacid generator. This composition utilizes the effect of the polymer to release a t-butyl ester group or t-butyl carbonate group by the action of an acid generated upon exposure to form an acidic group such as a carboxylic group or a phenolic hydroxyl group, which renders an exposed area on a resist film readily soluble in an alkaline developer.
Micronization of photolithography processes in recent years has been remarkable. In particular, in the lithography processes using a KrF excimer laser, the limit resolution has been decreasing close to one half of the light source wavelength or less. Therefore, requirements for the chemically amplified radiation-sensitive resin composition have become severer. The composition must not only exhibit higher resolution, but also be applicable to substrates with different reflection coefficients. In particular, when applied to a substrate with a large reflection coefficient, effects of standing waves and swing curves must be minimized. To this end, it is essential to control radiation transmittance. One method of reducing radiation transmittance is increasing the amount of a photoacid generator with a low radiation transmittance. However, this method is not necessarily appropriate in view of resist performance. The addition of a third component, such as a dye, is considered to be more appropriate.
Japanese Patent Application Laid-open Publications No. H07-319155 and No. H11-265061 proposes the addition of an anthracene compound as a dye to control the radiation transmittance of chemically amplified radiation-sensitive resin compositions. However, merely adding a compound with a low radiation transmittance may impair performance as a resist, such as decreased resolution and incomplete development. In addition, since anthracene compounds are generally sublimative, the exposure apparatus may be adversely affected. Moreover, many anthracene compounds exhibit insufficient compatibility with resin components and additives contained in chemically amplified radiation-sensitive resin compositions.
Japanese Patent Application Laid-open Publication No. H10-120628 discloses a carboxylic acid derivative having a tricyclic aromatic skeleton, such as an anthracene skeleton, with a carboxyl group bonded via a divalent hydrocarbon group or an oxygen atom, the carboxyl group being protected with a group unstable in the presence of an acid. The patent application describes that the carboxylic acid derivative exhibits superior light absorption properties and is suitable as an additive to chemically amplified radiation-sensitive resin compositions.
However, in view of the technological development in the photolithographic process requiring increasingly stringent performance accommodating the rapid progress of micronization, development of a novel compound useful as an additive to a chemically amplified radiation-sensitive resin composition responsive to deep ultraviolet rays and the like, capable of suitably controlling radiation transmittance, being only slightly sublimative, and exhibiting superior compatibility with other components in the radiation-sensitive resin composition still remains as an important technological subject.
An object of the present invention is to provide a novel anthracene derivative which, when used as an additive to a radiation-sensitive resin composition useful as a chemically amplified resist responding to active radiation, for example ultraviolet rays such as a KrF excimer laser, ArF excimer laser, and F2 excimer laser, can suitably control radiation transmittance, can effectively control line width variation in resist patterns due to fluctuation in the resist film thickness without impairing resolution performance, is only slightly sublimative, and exhibits superior compatibility with other components in the composition.
The above object can be solved in the present invention by an anthracene derivative of the following formula (1), 
wherein R1 groups individually represent a hydroxyl group or a monovalent organic group having 1-20 carbon atoms, n is an integer of 0-9, X is a single bond or a divalent organic group having 1-12 carbon atoms, and R2 represents a monovalent acid-dissociable group.
The above object can be further achieved in the present invention by a radiation-sensitive resin composition comprising (A) the anthracene derivative of the above formula (1), (B) a resin insoluble or scarcely soluble in alkali, but becomes alkali soluble in the presence of an acid, and (C) a photoacid generator.
Other objects, features and advantages of the invention will hereinafter become more readily apparent from the following description.